Fetal Imaging & Phenotyping SIG Update

Stephanie Dukhovny and Fionnuala Mone
Co-Chairs, Fetal Imaging and Phenotyping Special Interest Group

The Imaging and Fetal Phenotype Special Interest group met at the 26th International Conference on Prenatal Diagnosis and Therapy in Montreal this year. Our meeting highlighted cases presented by Drs. Samantha Doyle, Yuval Yaron, Teresa Sparks, and Neeta Vora. These presentations focused on expanding fetal phenotypes of pediatric genetic disorders and sparked a lively conversation that ranged from variant interpretation to collaborating on case reports.

This year, Prenatal Diagnosis has also displayed the importance of fetal imaging and phenotyping to compliment the optimization of the diagnostic yield of a range of genomic testing strategies. This starts out from the first trimester as demonstrated from Bardi, et al. "Additional value of advanced ultrasonography in pregnancies with two inconclusive cell-free DNA draws," demonstrating the importance of a detailed fetal anatomy scan in interpretation of NIPT results. With the advances in genomic sequencing, novel in-utero phenotype-genotype correlations are being detected as demonstrated in Qiu-Xia, et al. "Prenatal diagnosis of Coffin-Siris syndrome: What are the fetal features?" and Swanson, et al. "Prenatal phenotype of 47, XXY (Klinefelter syndrome)."  

In prenatal exome sequencing, accurate phenotyping is paramount as demonstrated by Swanson, et al. "The utility of pathologic examination and comprehensive phenotyping for accurate diagnosis with perinatal exome sequencing" where they describe four cases where postnatal examination still has the potential to add value where prenatal diagnosis has been incomplete. In utero MRI remains a vital tool, offering additional phenotypic information over and above ultrasound as described by Tang, et al. "A comparison of the accuracy of fetal magnetic resonance imaging and ultrasonography for the diagnosis of fetal congenital malformations of the spine and spinal cord." 

In this year’s special issue on fetal sequencing, Mellis et al. Diagnostic yield of exome sequencing for prenatal diagnosis of fetal structural anomalies: A systematic review and meta-analysis, it is highlighted that different phenotypic subgroups (e.g., skeletal anomalies) have a more optimal diagnostic yield with prenatal exome sequencing than with other anomalies such as an isolated elevated nuchal translucency.